Fluid system and valve assembly therefor



y 1966 H. J. STACEY 3,251,277?

FLUID SYSTEM AND VALVE ASSEMBLY THEREFQR Filed April 25, 1964 4 Sheets-Sheet 1 2 TANK 3 (I; K INVENTOR. V [way If. STACEY BY J ww mgm ATTORNEYS H. J. STACEY May 17, 1966 NVEN HUGH J. STACEY BY mmw ATTORNEYS May,17, 1966 H. J. STACEY FLUID SYSTEM AND VALVE ASSEMBLY THEREFOR Filed April 25, 1964- 4 Sheets-Sheet 5 SPOOL DETENT MECHANISM 2 m0 mm 0 M54 M M m ma SPOOL CENTERING MECHANISM 2| 6 ATTORNEYS y 1966 H. J. STACEY 3,251,277

FLUID SYSTEM AND VALVE ASSEMBLY THEREFOR Filed April 23, 1964 4 Sheets-Sheet 4 I ll "I N II :I 5' I In 99? L5 87 95 H Q] Q 1 r 5 I w ":9 H n 90 84 34 65 80 46' TO SWITCHES i 5 I06 TO RETURN PORT IOI INVENTOR 50 05 HUGH 1/. STACEY VALVE BY ATTORNEYS United States Patent 3,251,277 FLUID SYSTEM AND VALVE ASSEMBLY THEREFQR Hugh J. Stacey, Chesterland, Ohio, assignor to Parker- Hanuifin Corporation, Cleveland, ()hio, a corporation of Ohio Filed Apr. 23, 1964, Ser. No. 362,153

12 Claims. (Cl. 91 -414) The present invention relates generally as indicated to a fluid system and valve assembly therefor, and more particularly to a fluid system and valve assembly which effects automatic bucket or scoop leveling during the raising of the main boom arm of a front end loader and like equipment.

Hitherto, it has been conventional practice to provide a front end loader with a hoist cylinder for raising and lowering the pivotally mounted boom of the tractor; with a bucket control cylinder for manipulating the bucket pivotally mounted at the free end of the boom between a digging or scooping position, a tilted back position for holding a load therein, and a dumping position whereat the load is dumped therefrom; and with mechanical link means on the boom extending to the tractor and bucket cylinder respectively for maintaining the bucket in its load holding position while the boom is being raised.

Accordingly, it is a principal object of this invention to provide a fluid system and valve assembly therefor in which bucket leveling is accomplished hydraulically, thus dispensing with complex and expensive mechanical link arrangements which heretofore have been used for that purpose.

It is another object of this invention to provide a fluid system and valve assembly therefor of the character indicated which has means associated with the control valve mechanism to prevent operation of the bucket control cylinder when the boom is in raised position in such a manner as to dump the load in the bucket backward onto the operator of the front end loader.

It is another object of this invention to provide a novel form of multiple spool valve assembly which requires only the operation of the valve spool to the boom hoisting position to effect raising of the boom and automatic retention of the bucket in load holding position during raising of the boom, the bucket cylinder control spool being left in neutral position but having passages to con duct the fluid displaced by the boom cylinder to the bucket cylinder.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodimentsof the invention, these being indicative, however, of a few of the various ways in which the principle of the invention may be employed.

In said annexed drawings:

FIG. 1 is a schematic piping diagram showing a fluid system including a two-spool valve assembly for controlling the operation of boom hoist and bucket tilt cylinders, the valve assembly being shown in elevation;

FIG. 2 is a bottom plan view of the valve shown in FIG. 1;

FIG. 3 is' a cross-section view through the valve assembly taken substantially along the line 3-3, FIG. 2;

FIG. 4 is a cross-section view taken substantially along the line 44, FIG. 2;

FIG. 5 is a cross-section view similar to FIG. 3 except assembly that the spool for the hoist cylinder is selective in operation, that is, to operate the hoist cylinder to raise the boom with or without the automatic hydraulic bucket leveling, and also showing a safety feature whereby the bucket control spool is locked against movement in a direction to preclude back tilting of the bucket when the boom has been hoisted thus to prevent dumping of the load on the operator of the front end loader; and

FIG. 6 illustrates another form of locking mechanism to prevent operation of the bucket tilt spool in a direction to dump the load in the bucket on the operator when the boom has been hoisted, said FIG. 6 being generally similar to FIG. 3 with the addition of a lock-out plunger and normally closed solenoid valve.

Referring now more particularly to the drawing, and

first to FIG. 1, the fluid system as a whole comprises a tank or reservoir 1, a pump 2 which draws fluid from the reservoir through conduit 3, and delivers it under pressure through conduit 4 to the inlet port 5 of a directional control valve assembly 6, the fluid being returned by way of the conduit 7 to the reservoir 1 in the event that both valve spools 8 and 9 are in neutral position. In FIG. 1 the valve spool 3 controls actuation. of the bucket tilt cylinder 1% and to this end the valve housing 11 is provided with cylinder ports 12, 12 which are connected by the conduits 14, 15 with the opposite ends of the bucket tilt cylinder 10. The other valve spool 9 controls the operation of the boom hoist cylinder 16 and to that end the valve housing 11 is provided with cylinder ports 17, 17 which are connected by means of the conduits 18, 19 to the opposite ends of the boom hoist cylinder 16. In FIG. l'the reference numerals 20 and 21 denote the detent and spool centering mechanisms, respectively, for the spools 8 and 9 which are effective to yieldably retain the respective spools in one or more operating positions and to automatically restore the respective spools to their neutral positions when the detent positioning stops have been overcome by manual force applied on the respective spools.

Referring now to FIGS. 3 and 4 which illustrate the valve construction in detail, it can be seen therefrom that the valve housing 11 is provided with two parallel bores 23, 24 in which the respective spools 8, 9 are axially reciprocable. Each bore is intersected axially therealong starting at the middle by a conventional bypass arrangement 25, 26 through which the inlet port 5 and the return port 27 are in fluid communication when both spools 8 and 9 are in neutral position as shown in FIG. 3; by a pair of pressure feed passages 28, 28 and 29, 29 straddling the bypass passage; by a pair of cylinder passages 12, 12 and 17, 17 which lead to the aforesaid cylinder ports; and by a pair of return passages 30, 30 which communicate with the bypass passage 26 and return port 27. The pressure feed passages 28, 28 and upper one 29 are communicated with the portions and 26 of the bypass passage upstream of the respective spools 8 and 9 through check valves 31 therein which prevent reverse flow from one cylinder to the other in the event that one cylinder has a greater load thereon than the other. Between the inlet chamber 32 and return passage is a pilot-operated relief valve assembly 34 which limits the maximum pressure of the system.

The front end loader herein shown comprises a tractor T with a pair of boom arms 35 pivoted thereto at 36 and a bucket or scoop 37 pivoted at 38 to the free ends of said boom arms 35.

Referring now to the bucket tilt circuit, it can be seen that when the bucket spools is moved downwardly or upwardly from the neutral position, the bypass passage 25 will be closed and fluid under pressure will be conducted to one end or the other of the bucket tilt cylinder through adjacent passages 28 and 12 and the return flow from the other end of the bucket tilt cylinder 10 will be conducted to the reservoir 2 through the other adjacent passages 12 and 31 With reference to the boom hoist circuit, communication between the lower cylinder passage 17 and the lower return passage is blocked by the sleeve 48, and the lower feed passage 29 leads to the port 41 of the manifold housing 42 which is bolted or otherwise secured to the valve housing 11. Passages 43 and 44 lead from port 41 to the lower cylinder passage 12 of the bucket tilt circuit via a check valve 45. It is noted that there is a relief valve 46 communicating the lower feed passage 29 with the return port 27, said relief valve opening if the piston in the bucket tilt cylinder 16 reaches the end of its stroke.

The manifold housing 42 also has an upper cylinder passage 54 which communicates with the upper cylinder passage 12 of the housing 11 and with a return passage 48 leading to port 49 and return port 27 via a flow control valve 50 which comprises a plunger 51 exposed to fluid pressure in the passage 43 and a tapered flow control portion 52 which establishes control of flow from the cylinder passage 12 to the return passage 48. The flow control valve member 51 is biased by the spring 53 to normally close communication between the cylinder passage 12 and the return passage 48 until such time as the pressure in the passage 43 acting on the area of the plunger 51 is sufficient to overcome the biasing force of the spring 53.

From the foregoing explanation, it can be seen that when the boom hoist spool 9 is moved downwardly, the bypass passage 26 is closed and fluid under pressure enters the upper feed passage 29 via the check valve 31 and flows through the upper cylinder passage 17 to the lower end of the boom hoist cylinder 16, thus to swing the boom upwardly about its pivot 36. The displaced fluid from the upper end of the boom hoist cylinder 16 returns through the conduit 19 and now flows from the lower cylinder passage 17 to the lower feed passage 29 and through the passages 43, 44 in the manifold housing 42 and check valve into the lower cylinder passage 12 of the bucket tilt circuit. In this way, the fluid under pressure flows through the conduit 14 into the head end of the bucket tilt cylinder 10 to maintain the bucket 37 in level position as the boom 35 is being raised, the displacement of the boom hoist cylinder 16 being related to the displacement of the bucket tilt cylinder 10 to maintain the bucket in approximately level load-holding position. The displaced oil from the rod end of the bucket tilt cylinder 10 is returned to the reservoir 1 via the upper cylinder passage 12 and manifold housing passages 54, 48 via the flow control valve which is now opened by pressure in passage 43. It is to be noted that the return flow from the bucket cylinder 10 can only occur when the fluid pressure acting on the plunger 51 is sufficient to actuate the flow control valve. Thus the bucket 37 is prevented from moving any more than is necessary to maintain it in approximately level condition, since if it tends to move faster than the displacement of oil from the boom hoist cylinder 16, the pressure in the passage 43 will drop with consequent closing of the flow control valve 50. Of course, the bucket cannot move in the other direction because of the positive displacement of oil from the boom hoist cylinder 16 per increment of hoisting movement.

If the bucket 37 is rolled forward before the boom lifting operation is started and the bucket cylinder 18 bottoms out while being lifted, the relief valve 46 in the passage 29 will allow the return oil from the boom cylinder 16 to return to the reservoir 1, whereby the boom lifting operation may be completed. The bucket tilt spool 8 can at any time take over the operation of the bucket 37 and override the automatic leveling.

Lowering of the boom 35 is done in the normal manner without leveling of the bucket 37. Thus, the boom spool 9 will be shifted upwardly from the neutral position until the slots 56 in the spool 9 are registered with the lower cylinder passage 17 and the slots 57 are registered wit the upper feed passage 29, whereby fluid under pressure flows through the upper check valve 31 into the upper feed passage 29 and through the slots 57, the bore 58 in the spool 9, and the slots 56' to the lower cylinder passage 17 from whence the fluid flows through the conduit 19 to the upper end of the boom hoist cylinder 16. The fluid displaced by the lower end of the boom hoist cylinder 16 is conducted to the reservoir 1 via the conduit 18 and the intercommunicating upper cylinder and return passages 17 and 38 via the restrictor sleeve 59 to build up a desired back pressure to prevent cavitation in the upper end of the boom hoist cylinder and too rapid lowering of the boom 35.

In the instant example, the boom hoist spool 9 is of the 4 way float type having a float position upward beyond the aforesaid boom lowering position. In this case, the cylinder passages 17, 17 are in fluid communication with one another through the bore 58 in the spool, and

' the orifice 60 through the land into the bore 58 is at this time in fluid communication with the return port 27 so that excess fluid from the lower end of the boom cylinder will be returned to the reservoir through the orifice 60' and at the same time back pressure will build up to maintain the upper end of the boom hoist cylinder 16 filled with fluid.

Referring now to FIG. 5, there is associated with the bucket spool 65 a solenoid 67 which has an armature 68 engageable under the shoulder 69 when the solenoid 67 is energized by the closing of the switches 70 and 71 in series. Thus, when the boom 72 reaches its uppermost position a cam 73 thereon closes the switch 70, and a cam 74 on the bucket tilt cylinder 75 closes the other switch 71. When the solenoid armature 68 is thus moved inward, the bucket tilt spool 65 is locked against downward movement, whereby the operator cannot roll the bucket 76 backward to dump the load upon himself. The groove 78 in the spool 65 is wide enough to permit movement of the spool upwardly to roll the bucket 76 forwardly to thus dump the load forwardly while the boom 72 is in raised position. The spool 65 and its various ports are-otherwise the same as the spool 8 of FIG. 3, already described. Accordingly, a further discussion of the details and operation of spool 65 is not thought to be necessary.

Another difference in the FIG. 5 valve assembly from that shown in FIGS. 1 to 4, is that the float spool 80 for the boom cylinder 81 is selective in operation insofar as bucket leveling is concerned. When the float spool 80 is moved downwardly from the neutral position shown, the upper feed passage 82 is placed in communication with the upper cylinder passage 83 to conduct oil under pressure into the lower end of the boom hoist cylinder 81 and the return flow from the upper end of the boom hoist cylinder 81 is through the intercommunicating lower cylinder passage 84 and the lower return passage 85, communication yet being blocked by the land 86 between the lower cylinder passage 84 and the bucket leveling passage 87 which communicates with port 41 of the manifold housing 42, as does the lower feed passage 29 in the FIG. 3 embodiment. If it is desired to accomplish automatic hydraulic bucket leveling, the spool 80 is moved down farther yet maintaining fluid communication between the upper feed and upper cylinder passages 82 and 83 while the land 86 closes communication between the lower cylinder and return passages 84 and and communication between the lower cylinder passage 84 and the leveling passage 87 is opened via the groove 89 in the spool 80. Thus, the return oil from the upper end of the boom hoist cylinder 81 flows through the passage '90 and bore 91 of the spool 80, the slots 90 being at this time in register with the respective upper feed passage 82 and lower cylinder passage 84, thus to conduct fluid under pressure through the spool bore 91 to the upper end of the boom hoist cylinder 81. The fluid returns to the reservoir 1 from the lower end of the boom hoist cylinder through the conduit 92 and the now registering upper cylinder passage 83 and upper return passage 85 via metering slots 93 in the land 94 of the spool. After the spool 80 is moved still farther upwardly, the upper and lower'cylinder passages 83 and 84 are in fluid communication with each other, and the orifice 95 which leads through the land 96 into the spool bore 91 is in communication with the reservoir 1 so that excess oil displaced from the lower end of the cylinder 81 flows into the return chamber 97 and thus builds up a pressure in the fluid circuit leading to the upper end of the boom hoist cylinder 81.

In lieu of the solenoid arrangement contemplated in FIG. 5, the manifold housing 100 as shown in FIG. 6 may be inserted between the bucket tilt cylinder 10 and the lower cylinder port 12 with the conduit 14 leading to the cylinder passage portion 103 and the other cylinder passage portion 104 leading to the lower cylinder port 12.

A normaly closed solenoid valve 101 normally blocks fluid at the inlet from acting on the plunger 102 via a branch passage 110. However, when the solenoid valve 101 is opened by the closing of both switches 70 and 71, it permits high pressure to pass through branch passage 110 and act on the plunger 102 to move it upwardly to prevent return flow of fluid from the bucket tilt cylinder or 75 to the lower cylinder passage 12 via the cylinder passage portion 103 and the other cylinder passage portion 104. In this way, even if the operator moves the bucket spool 8 or 65 in a direction to roll back the bucket, the bucket will not roll back as long as the boom 35 or 72 is in raised position with the cam 73 on the boom and the cam 74 on the bucket cylinder closing the two switches 70 and 71. However, as soon as the boom 35 or 72 is lowered to open switch 70 the solenoid valve 101 closes and the pressure in the chamber 105 and return passage 106 are equalized through the orifice 107 to permit the spring 108 to move the plunger 102 to the position shown to elfect communication between the upper and lower cylinder passage portions 103 and 104. The check valve 109 in the plunger 102 permits flow in one direction only, that is, from the lower passage portion 104 into the upper passage portion 103 as is necessary for permitting dumping of the bucket forwardly when solenoid valve 101 is open and the plunger 102 is in the up or blocking position.

From the foregoing, it can thus be seen that the present invention provides in a front end loader, for example, hydraulic leveling of the bucket as the boom is being raised thus to eliminate complicated mechanical linkages heretofore employed. Moreover, certain forms of the present invention also provide for locking so that the bucket cannot be rolled back while the boom is in its elevated position. Of course, if the bucket is in dumping position, the cam 74 thereon will not engage the switch 71 and thus the bucket spool 8 or 65 may be actuated to roll the bucket back even to rolled-back rear dumping position, but since the load will have been dumped therefrom, it is immaterial that the solenoid armature 68 in the form of FIG. 5 cannot move in under the shoulder 69. However, the structure of FIG. 6 is foolproof in this respect, in that the moment that the second switch 71 is closed by roll back of the bucket, the solenoid valve 101 is opened and the high pressure in the inlet 5 acts 6 on the plunger 102 to block further roll-back of the bucket.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

1. A fluid power system comprising at least two fluid motors; a pump; a reservoir; and a directional control valve assembly operatively connected to said motors, pump,

and reservoir for selective actuation of said motors by fluid under pressure delivered by said pump upon movement of corresponding valve members in said assembly from inactive positions blocking flow of fluid from said pump to said motors to active positions, fluid displaced by said motors being returned to said reservoir via said assembly; said assembly having a passage therein which, when one valve member is in active position and another valve member is in inactive position, conducts fluid displaced by-the associated one motor to the associated another motor; and a valve plunger means in said passage adapted to be moved to a position permitting the displaced fluid from said another motor to return to said reservoir only when the pressure of fluid entering said another motor from said one motor reaches a predetermined level.

2. A fluid power system comprising at least two parallel motors; a pump; a reservoir; and a directional control valve assembly operatively connected to said motors, pump, and reservoir for selective actuation of said motors by fluid under pressure delivered by said pump upon movement of corresponding valve members in said assembly from inactive positions blocking flow of fluid from said pump to said motors to active positions, fluid displaced by said motors being returned to said reservoir via said assembly; said assembly having a passage therein which, when one valve member is in active position and another valve member is in inactive position, conducts fluid displaced by the associated one motor to the associated another motor; and locking means associated with said motors operative automatically upon a predetermined actuation of both of said motors as aforesaid to preclude actuation of said another motor in the reverse direction.

3. The system of claim 2 wherein said locking means comprises a solenoid coil, switch means operative to energize said solenoid coil in response to such predetermined actuation of said motors, and a solenoid armature means which is moved into engagement with said another valve member upon energization of said coil to prevent movement of said another valve member to an active position causing a reversal in the direction of actuation of said another motor.

-4. The system of claim 2 wherein said locking means comprises a fluid pressure actuated valve plunger, which, when actuated, closes another passage in said assembly between said assembly and said another motor, and means for conducting fluid under pressure to act on said plunger.

5'. The system of claim 4 wherein said last-mentioned means comprises a solenoid-operated normally closed valve which is opened by closing of switches in response to such predetermined actuation of said motors to conduct such fluid under pressure to act on said plunger.

6. The system of claim 5, wherein there is a check valve means in said another passage which permits the flow of fluid therethrough in a direction permitting continued actuation of said another motor in the same direction upon movement of said another valve member to the proper active position. i

7. A valve assembly for controlling the actuation of first and second double acting fluid motors, comprising a valve housing having an inlet .port for connection with a fluid reservoir, and first and second pairs of motor ports for connection with the respective motors; first and second directional control valve in said housing actuatable from an inactive position blocking fluid communication between said inlet port and said first and second pairs of mot-or ports to at least two active positions selectively communicating said inlet port with either one of the motor ports of said pairs of motor ports for actuation of the respective fluid motors; said housing having a passage which when said second valve is in one active position and said first valve is in inactive position, communicates one motor port of said second pair of motor ports with one motor port of said first pair of motor ports, whereby fluid displaced from the second motor is conducted through said passage to actuate the first motor; and plunger means in said passage yieldably urged by spring 8 means to a first position blocking the flow of the displaced fluid from said first motor to said return port, said plunger means having one end exposed to the fluid entering said first motor from said second motor urging said plunger means to a second position permitting the flow of such displaced fluid from said first motor to said return port when the pressure of such fluid entering said first motor is suflicient to overcome the bias of said spring means.

8. A valve assembly for controlling the actuation of first and second double acting fluid motors comprising a valve housing having an inlet port for connection with a fluid pressure source, a return port for connection with a fluid reservoir, and first and second pairs of motor ports for connection with the respective motors; first and second directional control valves in said housing actuatable from an inactive position blocking fluid communication between said inlet port and said first and second pairs of motor ports to at least two active positi-ons selectively communicating said inlet port with either one of the motor ports of said pairs of motor ports for actuation of the respective fluid motors; said housing having a passage which when said second valve is in one active position and said first valve is in inactive position, communicates one motor port of said second pair of motor ports with one motor port of said first pair of motor ports, whereby fluid displaced from the second motor is conducted through said passage to atctuate the first motor; and locking means in said housing operative automatically upon a predetermined actuation of both of such motors as aforesaid to prevent actuation of such first motor in the opposite direction.

9. The assembly of claim 8 wherein said locking means comprises a solenoid armature means which is adapted to be moved into engagement with said first valve to prevent movement thereof in one direction to a position causing a reversal in the direction of actuation of said first motor.

10. The assembly of claim 8 wherein said locking means comprises a fluid pressure actuated valve plunger which, when actuated, closes another passage in said assembly between said assembly and said first motor, and means for conducting fluid under pressure to act on said plunger.

11. The assembly of claim 10 wherein said lastmentioned means comprises a solenoid-operated normally closed valve which is opened upon such predetermined actuation of said motors to conduct fluid under pressure from said inlet port to act on said plunger.

12 The assembly of claim 11 further comprising a check valve means in said another passage which permits the flow of fluid through said another passage in a direction permitting continued actuation of said first motor in the same direction upon movement of said first valve to a selected active position.

References Cited by the Examiner UNITED STATES PATENTS 6/1961 Hemings -52 X 3/1965 Krehbiel 137596.12 

1. A FLUID POWER SYSTEM COMPRISING AT LEAST TWO FLUID MOTORS; A PUMP; A RESERVOIR; AND A DIRECTION CONTROL VALVE ASSEMBLY OPERATIVELY CONNECTED TO SAID MOTORS, PUMP, AND RESERVOIR FOR SELECTIVE ACTUATION OF SAID MOTORS BY FLUID UNDER PRESSURE DELIVERED BY SAID PUMP UPON MOVEMENT OF CORRESPONDING VALVE MEMBERS IN SAID ASSEMBLY FROM INACTIVE POSITIONS BLOCKING FLOW OF FLUID FROM SAID PUMP TO SAID MOTORS TO ACTIVE POSITIONS, FLUID DISPLACED BY SAID MOTORS BEING RETURNED TO SAID RESERVOIR VIA SAID ASSEMBLY; SAID ASSEMBLY HAVING A PASSAGE THEREIN WHICH, WHEN ONE VALVE MEMBER IS IN ACTIVE POSITION AND ANOTHER VALVE MEMBER IS IN INACTIVE POSITION, CONDUCTS FLUID DISPLACED BY THE ASSOCIATED ONE MOTOR TO THE ASSOCIATED ANOTHER MOTOR; AND A VALVE PLUNGER MEANS IN SAID PASSAGE FLUID TO BE MOVED TO A POSITION PERMITTING THE DISPLACED FLUID FROM SAID ANOTHER MOTOR TO RETURN TO SAID RESERVOIR ONLY WHEN THE PRESSURE OF FLUID ENTERING SAID ANOTHER MOTOR FROM SAID ONE MOTOR REACHES A PREDETERMINED LEVEL. 